The grain truck is a 47-53? If a normal 1.5 or 2 ton then an 8.3L Cummins has very little chance of fitting. Some have done the 5.9L Cummins in them and its a terribly tight fit with much sheet metal work to do so.
If the truck is a large GMC it may fit the 8.3L Cummins.

Your tape measure will answer for sure.

Grigg

•1951 GMC 250 in the Project Journals
•1948 Chevrolet 6400 - Detroit Diesel 4-53T - Roadranger 10 speed overdrive - 4 wheel disc brakes
•1952 Chevrolet 3800 pickup
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"First, get a clear notion of what you desire to accomplish, and then in all probability you will succeed in doing it..." -Henry Maudslay-